The present invention relates to a seatbelt retractor for use in a passenger car, etc., in order to ensure the safety of a vehicle occupant.
The seatbelt retractor must be installed in order to ensure the safety of a vehicle occupant upon an accident, such as a passenger car collision, and various types thereof have been developed. An example of the simplest structure thereof is shown in FIG. 11.
A spring cover 21, which is a supporter at one side of the seatbelt retractor, is provided with a bearing 21a arranged therein, into which a shaft 22a of a spool 22 is fitted so as to rotate while an urging force in the retracting direction is applied to the shaft 22a by a spring. Around the spool 22, a seatbelt is wound.
Inside the spool 22, a concave fitted portion (not shown) is formed, into which one end of a torsion bar 23 is fitted. The other end of the torsion bar 23 is fitted into a concave fitted portion (not shown) formed in a locking base 24. A shaft 24a of the locking base 24 passes through a hole 25a of a lock gear 25 so as to fit into a bearing (not shown) of a retainer 26, which is a supporter in the other side of the seatbelt retractor.
Such a mechanism results in supporting the spool 22 at its rotating shaft by the spring cover 21 and the retainer 26, and rotating the spool 22 so as to retract the seatbelt by means of the urging force of the spring. The spring cover 21 and the retainer 26 are fixed at both ends of a base frame 28, so that the spool 22 is accommodated within the base frame 28.
In these structural elements, the locking base 24 and the lock gear 25 are relatively rotatable by a predetermined angle, so that the lock gear 25 is urged by a spring 29 relative to the locking base 24 in the direction of extracting the seatbelt so as to approach the limit of the relative rotation.
When the seatbelt is extracted in a normal state, since there is no rotational resistance against the lock gear 25, the lock gear 25 can not overcome the urging force of the spring 29 to thereby rotate integrally with the locking base 24.
Even when the locking base 24 is rotated in the retracting direction as the spool 22 is rotated by the spring force, the lock gear 25 rotates integrally with the locking base 24 because the lock gear 25 is designed originally to approach the limit of the rotation relative to the locking base 24 in this direction as mentioned above.
When rapid extraction of the seatbelt is produced due to a collision or the like, a flywheel 30 accommodated within the lock gear 25 is displaced by overcoming the urging force of a spring 31, so that the lock gear 25 can not rotate relatively to the retainer 26 and the rotation is stopped.
Then, the rocking base 24 rotates relatively to the lock gear 25 against the urging force of the spring 29. A mechanism is constructed such that a pawl 32 accommodated in the locking base 24 protrudes outside by this relative rotation, and a gear of the externally protruded pawl 32 is brought into engagement with a gear section 28a formed in the base frame 28, thereby also stopping the rotation of the locking base 24.
Accordingly, rotation of the torsion bar 23 is also stopped and the spool 22 is allowed to rotate only by an angle corresponding to a twist of the torsion bar 23. Therefore, the spool 22 is thereafter rotated under a tension increasing as the seatbelt is extracted. The locking mechanism described above is generally called as xe2x80x9ca locking mechanism by a webbing sensorxe2x80x9d.
The description above only illustrates an outline of the seatbelt retractor and there are complex mechanisms for use as a mechanism for stopping rotation of the lock gear 25 by the movement of the flywheel 30 and a mechanism for protruding the pawl 32 outside, for example. However, the seatbelt retractor is known and is used in common, so that more detailed description may be not necessary for those skilled in the art. Moreover, it is irrelevant to the principal part of the present invention, so that the more detailed description is omitted.
However, in the conventional seatbelt retractor, since the lock mechanism is operated after the seatbelt is actually extracted rapidly, a time lag for operating the lock mechanism may be developed. When the seatbelt is suddenly extracted during wearing the seatbelt, the lock mechanism may also be operated, so that uncomfortable feeling or unpleasantness may be given to an occupant.
The present invention has been made in view of such a situation, and it is an object of the present invention to provide a seatbelt retractor which can promptly operate a lock mechanism upon an emergency, and moreover, it is another object to provide a seatbelt retractor which does not provide uncomfortable feeling or unpleasantness to the occupant due to locking produced when the seatbelt is extracted for wearing the seatbelt.
First means for solving the problems described above is a seatbelt retractor comprising a mechanism for locking the rotation in the extracting direction of the seatbelt retractor upon receiving a collision predicting signal from a collision predicting device, the mechanism being independent of the rotational movement of a spool (first aspect of the invention).
The collision predicting device detects a vehicle acceleration, a distance to a front car, a vehicle velocity, hard braking by the driver, and so forth so as to predict an accident such as a collision prior to occurrence of the accident on the basis of the detected information, and the device is already known. In the first means, at the time when receiving a collision predicting signal from the collision predicting device, rotation of the seatbelt retractor in the extracting direction is locked. Therefore, differently from a conventional retractor, extraction of the seatbelt can be locked before the seatbelt is actually extracted, so that operation cannot lag behind.
In addition, in this case, the phrase xe2x80x9clocking rotation in the extracting directionxe2x80x9d means completely locking actual rotation including locking while allowing the rotation via the torsion bar mentioned in the description of the related art.
Also, if removing the extraction-locking mechanism by detecting extracting the seatbelt using the flywheel mentioned in the description of the related art, even when rapidly extracting the seatbelt during wearing the seatbelt, the seat belt is not locked and thereby eliminating uncomfortable feeling or unpleasantness from an occupant.
In the second means for solving the problems, according to the first means, the mechanism for locking the rotation in the extracting direction of the seatbelt retractor comprises a ratchet gear having saw-blade teeth for use in a ratchet mechanism at the external periphery and directly connected to a rotational shaft of the seatbelt retractor or engaged with a gear directly connected to the rotational shaft, a pawl arranged to be engageable with the saw-blade teeth, a lever for driving the pawl so as to engage with and disengage from the saw-blade teeth, a rotational body for driving the lever via a torque limiter, and a motor for driving the rotational body (second aspect of the invention).
In the second means, in a steady state, the rotational position of the motor is located at a position that the pawl is not engaged with saw-blade teeth of the ratchet gear. Upon receiving a collision predicting signal, the motor rotates, and the rotational body is thereby rotated. The lever is thereby driven so as to drive the pawl to a position engaging with the saw-blade teeth of the ratchet gear. Therefore, the pawl and the ratchet gear form a ratchet mechanism, so that the ratchet gear can rotate in the seatbelt-retraction direction while cannot rotate in the extracting direction. Accordingly, the rotational shaft of the seatbelt retractor directly connected to the ratchet gear or connected thereto via a gear is also prevented from rotating in the extracting direction.
In this case, although the motor continues to rotate, because the torque limiter is arranged between the rotational body and the lever, a force for pushing the pawl by the ratchet gear is limited to a force determined by the torque limiter, so that rotation of the ratchet gear in the direction retracting the seatbelt cannot be prevented and the lever, etc. cannot be damaged.
In the third means for solving the problems, according to the first means, the mechanism for locking the rotation in the extracting direction of the seatbelt retractor comprises a ratchet gear having saw-blade teeth for use in a ratchet mechanism at the external periphery and directly connected to a rotational shaft of the seatbelt retractor or engaged with a gear directly connected to the rotational shaft, a pawl arranged to be engageable with the saw-blade teeth, a lever for driving the pawl so as to engage with and disengage from the saw-blade teeth, a rotational body for driving the lever, and a motor having a torque limiter for driving the rotational body (third aspect of the invention).
The third means is different from the second means only in using the motor having the torque limiter instead of the torque limiter between the lever and the rotational body. Because other mechanisms are identical, the fundamental operation and advantages thereof are the same as those of the second means. In the third means, since a standard motor having the torque limiter is used, any torque limiting mechanism is not specifically required. In addition, the torque limiter of the motor may be a limiter for limiting the maximum current value other than a mechanical one.
In the fourth means for solving the problems, according to the first means, the mechanism for locking the rotation in the extracting direction of the seatbelt retractor comprises a ratchet gear having saw-blade teeth for use in a ratchet mechanism at the external periphery and directly connected to a rotational shaft of the seatbelt retractor or engaged with a gear directly connected to the rotational shaft, a pawl which is arranged to be engageable with the saw-blade teeth and which rotates about a rotational pivot arranged in a fixed part of the seatbelt retractor, and a driving mechanism for driving the pawl so as to engage with and disengage from the saw-blade teeth via an elastic body (fourth-aspect of the invention).
In the fourth means, in a steady state, the position of the pawl driven by the driving device is located at a position that the pawl is not engaged with saw-blade teeth of the ratchet gear. Upon receiving a collision predicting signal, the driving device operates, and the lever is thereby driven via the elastic body so as to rotate the pawl to a position engaging the saw-blade teeth of the ratchet gear. Therefore, the pawl and the ratchet gear form a ratchet mechanism, so that the ratchet gear can rotate in the direction retracting the seatbelt while cannot rotate in the extracting direction. Accordingly, the rotational shaft of the seatbelt retractor directly connected to the ratchet gear or connected thereto via a gear is also prevented from rotating in the extracting direction.
In this case, because the elastic body is arranged between the driving device and the lever, a force of the ratchet gear for rotating in the direction retracting the seatbelt is absorbed by the elastic body so as not to prevent the rotation.
In the fifth means for solving the problems, according to the first means, the mechanism for locking the rotation in the extracting direction of the seatbelt retractor comprises a ratchet gear having saw-blade teeth for use in a ratchet mechanism at the external periphery and directly connected to a rotational shaft of the seatbelt retractor or engaged with a gear directly connected to the rotational shaft,
a pawl which is arranged to be engageable with the saw-blade teeth by rotation and which has a slotted hole fitted with a pin formed in a fixed part of the seatbelt retractor, and
a ratchet lever which is arranged to be connected to a reciprocation driving unit and has a rotational pivot of the pawl,
wherein when the reciprocation driving unit is located at a first position, the pawl rotational pivot of the ratchet lever is located at the first position while the pin is located at one end of the slotted hole so that the pawl is positioned apart from the ratchet gear, and wherein when the reciprocation driving unit is located at a second position, the pawl rotational pivot of the ratchet lever is located at the second position so that the pawl is located at an engageable position with the ratchet gear, and when the spool is rotated in the extracting direction at this state, the pawl rotates about the pawl rotational pivot so as to be stopped by abutment of the pin against the one end of the slotted hole so that rotation of the ratchet gear is stopped, while when the spool is rotated in the retracting direction, the pawl rotates about the pawl rotational pivot in the direction opposite to the aforementioned direction so that the rotation of the ratchet gear is allowed by positioning of the shaft at the other end of the slotted hole (fifth aspect of the invention).
In the fifth means, when the reciprocation driving unit is located at the first position, the pawl rotational pivot of the ratchet lever is located at the first position while the pin formed in the fixed part of the seatbelt retractor is located at one end of the slotted hole of the pawl. Thereby, the pawl is positioned apart from the ratchet gear so that the ratchet gear can rotate freely and rotation of the spool is not prevented.
When the reciprocation driving unit is located at the second position, the pawl rotational pivot of the ratchet lever is loss located at the second position so that the pawl is located at an engageable position with the ratchet gear. In this state, when the pin is located at the one end of the slotted hole of the pawl, the pawl is engaged with the ratchet gear while when the pin is located at the other end of the slotted hole, the pawl is not engaged with the ratchet gear.
When the spool rotates in the extracting direction, the pawl rotates about the pawl rotational pivot so as to prevent the ratchet gear from rotation by abutting of the pin against the one end of the slotted hole. Thereby, rotation of the spool is prevented.
When the spool rotates in the retracting direction, the pawl is pushed by the ratchet gear so as to rotate about the pawl rotational pivot in the direction opposite to the aforementioned direction, so that the pin is positioned at the other end of the slotted hole. In this case, the pawl is not engaged with the ratchet gear and rotation of the ratchet gear is allowed.
Sixth means for solving the problems, according to the fifth means further comprises an elastic body for urging the pawl in the rotational direction so as to bring the pawl into engagement with the ratchet gear (sixth aspect of the invention).
In the sixth means, since the pawl is urged by the elastic body in the rotational direction so as to bring the pawl into engagement with the ratchet gear, when the reciprocation driving unit is located at the second position and the ratchet gear rotates in the extracting direction, the rotation can be prevented by secure engagement between the ratchet gear and the pawl.
In the seventh means for solving the problems, according to the first means, having a mechanism for locking extraction of the seatbelt by detecting rapid extraction of the seatbelt (a locking mechanism by a webbing sensor), the mechanism for locking rotation in the extracting direction of the seatbelt retractor is a mechanism for actuating the locking mechanism by the webbing sensor) seventh aspect of the invention).
In the seventh means, the rotation in the extracting direction is locked by using the locking mechanism by the webbing sensor which is already assembled therein so that fewer additional instrument is required, thereby simplifying the structure.